The present invention relates to a method for controlling a wind turbine in which an electrical power fed into an electrical transmission network is increased in a boost operation via a generative deceleration of the generator.
The present invention relates to the control of a wind turbine for a mode of operation referred to as “virtual inertia.” For the purpose of grid support, an excessive amount of power, in particular effective power, is hereby fed into the electrical transmission network at short notice. For this purpose, the wind turbine emulates an underfrequency response of conventional synchronous generators. From the perspective of the energy balance, for feeding in the excessive power value, the rotational energy stored in the rotating mass of the wind turbine is converted at short notice and for a short time into electrical power via the generator and fed into the electrical transmission network. This process leads to more electrical power being fed into the transmission network in a boost operation than is converted and can be converted from the wind at short notice in the form of mechanical power. This leads to a decrease of the rotational speed and, linked therewith, of the stored rotational energy. At the end of the boost phase, the wind turbine is at an operating point with regard to rotational speed and torque that is not suitable for continuous operation. In a recovery phase, the wind turbine is then transferred to an operating point at which the rotational speed and torque are at a predetermined ratio that is optimal for taking up power from the wind and at which the wind turbine can be operated continuously. The method and procedure for virtual inertia are difficult to perform from a control engineering perspective.
A control arrangement for virtual inertia operation on a wind turbine is known from EP 2 532 888 A1, in which a two-state control (bang-bang control) is used to control the power generation while providing a power boost.